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 I

I connects certain verbs with infinitives. 

                                         +---I----+
        +-S-+--I-+                    +S-+-O--+   |
        |   |    |                    |  |    |   |
        I must  go to the store       I made him  go
Infinitive verb forms have "I-", conjoined with their complement connectors. In every case except "be", the infinitive form is the same as the plural form; therefore the same expression can be used. Plural-infinitive forms thus carry "(Ss- or I- or Wi-) & [complement]". (The Wi- is used to connect to the wall in imperative constructions.)

Modal verbs - "will", "may", "can", and the like - have I+ connectors; certain other verbs do as well, such as "do" and "help". Some verbs have I+ conjoined with O+, like "make" and "see", allowing an object followed by an infinitive. In these latter cases, the infinitive verb relates to the direct object of the main verb; it is similar in this respect to object+infinitive constructions like "I want him to go". Thus it is appropriate to include the O and I link in their own domain. For this reason, we label the I+ connector on such verbs as "I*j+", and make this an "urfl-domain"-starting link, including both the O and the I*j. (See "TOo".)

The word "to" also has an "I+", conjoined with "TO-", used in "to+infinitive" constructions.

Modal verbs are almost always used with an infinitive. However, occasionally the infinitive is omitted: "If you cannot do it, you should find someone who can". For this reason, modals are given "S- & (I+ or [[()]])"; this allows them to make no connection to an infinitive, with a cost of 2. "Do" is similar in this respect.

I*a: Indirect questions

"I*a" is used in object-type infinitival indirect questions. Here, a "to"+infinitive construction occurs, but in this case - unlike other "to"+infinitive constructions - the "to" is unable to connect back to another word. 
                   +--Bsw--+
                   |   +I*a+
                   |   |   |
        I wonder what to  buy

Post-processing insures that I*a is only used in the same group as a B*w or B*m, thus preventing unwanted uses of this connector.

In infinitival indirect questions with "where/when/how" - "I wonder where to go" - the question word instead makes a TOn connection with "to". See "TO: Other kinds of TO connectors".

I*d: bare infinitives after auxilliary do/did

"I*d" is used for infinitives following "do". 
             +--I*d-+-Ox-+
             |      |    |
          I did    see  him yesterday

I*g: Come/go serial verbs

"I*g" is used for bare infinitives following "come" or "go". 
             +--I*g-+-MVp-+-J-+
             |      |     |   |
            come  walk  with  me

I*j: Serial verbs with interposed objects

"I*j" is used for serial verbs with interposed objects. 
                          +----I*j---+
                  +---I---+-Ox-+     |
                  |       |    |     |
           you should   hear  him  sing

If: Filler-it

"If" connectors are used by post-processing to enforce the correct use of "filler-it" and "there". See "SF: Filler-it".

Iq: Praphrasing questions

"Iq" connectors are used to connect to paraphrasing questions. 
                          +--Iqv--+---I*d---+
                  +--Ss*q-+  +-Xd-+-SIs-+   +Osm+
                  |       |  |    |     |   |   |
     the big question.n is.v , did.v-d he do.v it ?

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